An Emergency Alert Service (EAS) that is provided over a wireless system, such as an IEEE 802.16 Rev D7 based networks (e.g. WiMAX), is becoming a regulatory requirement in many countries. In the US, the Federal Communications Commission (FCC) has issued rules for Commercial Mobile Alert Service (CMAS) in April 2008. In Japan, there is a request to deliver first emergency warning “Primary Notification” to a mobile station (MS) within four seconds. In Europe, a “Communication from Authority to individuals and the public during emergencies” is used, as it includes not only the warning service. Similarly, 3GPP and 3GPP2 are developing a Public Warning System (PWS) specification to use Cell Broadcast Short Messaging Service (SMS) to deliver a Textual Emergency Alert. In all of these cases, emergency information (from authorized sources) has to be sent only to all users in a given area. No subscription is necessary, and inbound roaming users also need to be supported.
IEEE 802.16 specifies three modes of service for a mobile: a) active mode, during which the MS and base station (BS) perform normal operations to exchange downlink and uplink (DL/UL) traffic, b) sleep mode, during which the MS conducts pre-negotiated periods of absence from the serving BS air interface. In this case, the MS and BS do not exchange DL/UL traffic during a sleep window, but the MS still retains all service flows. The mobile station includes a receiver that it only turns on at pre-determined period, i.e. wake-up period, for broadcast/multicast message, and unicast message, and c) idle mode, during which the MS becomes periodically available for DL broadcast traffic messaging without registration at a specific BS as the MS traverses an air link environment populated by multiple BSs, typically over a large geographic area. In this case, the MS only retains service flow for multicast-broadcast service, and all other service flows are deleted. In this mode, the mobile station only turns on its receiver at pre-determined period, i.e. wake-up period, for broadcast/multicast message. However, the current IEEE 802.16 Rev2 D7 air interface specification and WiMAX Forum Network Working Group (WMF NWG) R1.0 network specification do not specify an EAS solution to convey un-scheduled EAS notification, especially for mobiles that are in idle or sleep mode (collectively referred to herein as “inactive” mode), which only turn on its receiver at pre-determined wake-up period for broadcast/multicast message. Nor do these specifications include a method for the mobile station to be notified regarding which flows have been allocated for EAS support.
One solution for 3GPP and 3GPP2 is to use cell broadcast SMS for EAS, where the cell broadcast SMS may be repeatedly transmitted at pre-defined intervals, so the MS has a reasonably high probability of eventually receiving it. However this solution cannot be used for IEEE 802.16 based networks because the 802.16 air interface doesn't provide a solution for a SMS cell broadcast. Even if this functionality were supported by IEEE 802.16, an MS in inactive mode still cannot receive an SMS broadcast until it is transmitted in the mobile station's wake-up period, assuming the network constantly broadcasts the SMS.
Another solution is to force MSs in inactive mode to switch to active mode so that they can receive EAS. However, this solution results in excessive signaling in the network due to all of the inactive MSs which will need to go active, and this could overwhelm network resources.
Accordingly, what is needed is a technique to provide a WiMAX air interface and network signaling procedures for WiMAX systems to convey emergency alerts to MSs in inactive mode whose users may be impacted by an impending emergency. It would also be of benefit for the EAS to have priority over other wireless services such as Multicast Broadcast Services (MBS) and all other wireless services. It would also be advantageous for a user to have the ability to selectively receive alerts based on a priority level of the alert.
Skilled artisans will appreciate that common but well-understood elements that are useful or necessary in a commercially feasible embodiment are typically not depicted or described in order to facilitate a less obstructed view of these various embodiments of the present invention.